WHERE WHAT DOES TAKE?
Automobile fuel, whether diesel, gasoline or gas, consists of only three chemical elements combined into molecules: carbon C, hydrogen H and oxygen O. When burned - from a chemical point of view, this is a form of oxidation - long chains of atoms are destroyed, and the output we get carbon oxides CO2, hydrogen H2O, and all sorts of things. Both substances are harmless in principle, although they say that CO2 affects the weather.
This, however, is the case in the ideal case when the fuel burns “correctly” to the end. But the motors of the 21st century, alas, are imperfect and therefore part of the hydrocarbon chains may not decompose into atoms at all - get out of the motor in the form of far from harmless fragments of molecules (they are usually denoted as CH). It can decay, but not burn out, flying into the pipe in the form of soot. It may not burn out, giving the output a terribly poisonous carbon monoxide CO (what is the danger of substances from the exhaust pipe - see ЗР, 2003, No. 6).
Finally, the car’s engine does not run on pure oxygen, but on air, in which 78% nitrogen. At high temperatures, it also oxidizes - it produces very harmful NO and NO2, for short, referred to as NOX.
The horrors of the "gas attack" from cars frightened the inhabitants of Europe and the USA at the end of the 20th century. Legislators, supported by all kinds of associations of "green", began to limit the content of harmful substances in the exhaust. In Europe, environmental standards are called Euro, and the countdown began with Euro 0, introduced in 1988 as a mandatory requirement for obtaining type approval of a vehicle, and since 1990, when registering new cars.
WHAT NORMS ARE FOR
There are three ways to reduce harmful emissions: to optimize the combustion process of the mixture, to burn out what still has not burned in the cylinders, and to switch to alternative fuels. Today, engineers use all of these features.
The campaign for clean air began with the first option, and it cost the life of the good old carburetor. No, he could successfully prepare the mixture to this day, accelerating the car better than the most advanced injection systems. That's just the stability of the trouble parameters: an autonomous carburetor system does not understand the signals of electronic sensors (attempts to cross the carburetor with electronics were unsuccessful). The device is not able to accurately meter the fuel, taking into account many parameters, from air temperature to the degree of clogging of the nozzles. And without this, the neutralizers that settled in the exhaust tract at the same time as the introduction of Euro I would not work effectively. They burn out (oxidize) what is not burned in the cylinders.
It is clear: no matter how you improve the injection controller program, over time the parameters “go away” (for example, as nozzles become clogged). Therefore, with the introduction of stricter Euro II standards, an oxygen sensor (lambda probe) appeared that measures the composition of the “exhalation”. After the converter, it was another hundred dollars in the cost of the car.
Further more. Euro III “pressed” nitrogen oxides, which are too tough for conventional neutralizers: then they came up with exhaust gas recirculation to lower the temperature in the cylinders. The Greens took up emissions during engine warm-up; in order to render them harmless, it was necessary to move the converter close to the exhaust manifold or to apply electric heating. Cars are even cleaner, but more expensive.
Finally, the Euro IV introduced this year (when registering new cars they will become mandatory from January 2006) has further tightened emissions requirements in transient and starting conditions. Now, new cars can not do without an electronic gas pedal. Indeed, the mechanical throttle drive allowed the driver to stomp the pedal without thinking about the cleanliness of the exhaust, and the controller was forced to re-enrich the mixture during acceleration. Electronic damper makes the process smoother. So, ecology will sacrifice (to a certain extent) dynamics.
This, however, is far from all. Estimation of emissions according to Euro III standards is possible only with the help of expensive stands and equipment. They demanded from the manufacturers that the car is guaranteed to meet the standards for 80, 000 km! To be sure of this, since 2000 they made the installation of OBD on-board diagnostics mandatory on each machine. She closely monitors the operation of all nodes and immediately signals the driver about any malfunction that can cause a "foul smell" from your pipe.
Do you think this is the end of the story? Today, the European Commission is debating the issue of equipping cars with a more advanced OBM system (On-Board-Measurement - on-board measurement). Then the machine itself will measure the composition of the gases and record the results in the computer's memory. Arriving at the inspection, and the inspector will immediately see on the monitor how much you poisoned the air of his native city over the past year.
And now let's pay attention to the diesel engine: maybe it is easier to achieve a clean exhaust in it? At first it seemed that abandoning the pre-chamber, increasing injection pressure and electronic control would satisfy the ambitions of environmentalists. There it was! First, they clung to nitrogen oxides, which are difficult to fight in diesels: just “crush” how black smoke of unburned carbon will fall from the pipe. Then they demanded that the soot microparticles be removed almost completely … Bottom line: today diesel engines comply with Euro IV thanks to sophisticated injection, recirculation systems, NOx storage converters and particulate filters.
As the last two devices become clogged, the motor briefly switches to a mode in which the temperature of the gases rises sharply: harmful substances are burned out. Such systems are also expensive. More recently, the German government decided on tax benefits of 350 euros for owners of new cars with diesel particulate filters and 250 euros for those who will equip them with their old "diesel car". (And unclean diesel engineers - shame and disgrace … plus an increase in tax from 2008 by 20%.)
In light of the foregoing, the solution is seen, firstly, in the transition from gasoline to natural gas - with it the engine fulfills Euro IV standards with less blood or from diesel fuel to dimethylether (our Russian know-how). Secondly, the synthesis of liquid fuel from the same gas (even better from food waste or biomass) is considered to be a promising area - there will be no sulfur or aromatic hydrocarbons in it. And then Euro V will become an everyday and affordable reality.
AND WE HAVE…
And we have at the time of preparation of the document, the document finally introducing Euro II standards from January 1, 2006, was awaiting approval by the government. Has the carbureted dinosaurs come to an end?
Then you should think about revising the tax system so that it economically stimulates the acquisition of cleaner cars. In the meantime, in the registration documents there is not a word about the environmental parameters of the car.
But in any case, we, the people, ourselves will make the air of cities cleaner, changing to more and more modern foreign cars.
ONE TWO THREE FOUR FIVE…
If you look at the European standards (tab.), It will catch your eye that the standard for CO for Euro III is softer than for Euro II. But the measurement procedure is tougher: earlier gases were collected for analysis 40 seconds after starting the engine at room temperature. Now this is done at minus 7 ° C, and after starting the engine runs on an enriched mixture, and the converter is still cold.
There is still a debate on passenger cars on Euro V - when and for whom to make them mandatory. (EU lawmakers promise to decide soon.) Manufacturers, as they can, are pushing back - it is possible to reduce soot emissions by 10 (!) Times only at the cost of installing complex filters worth 200-400 euros. But the market is already stagnant. It seems, however, that the "greens" will win again under the slogan: "Death stands at the threshold of Germany in the form of microparticles."